The present invention relates to a device for replacing a heart valve by a percutaneous route.
Replacing a defective heart valve is currently usually performed by opening up the thorax, placing the patient under extra-corporal circulation, temporarily stopping the heart, and opening up the heart so as to cut away and replace the valve.
These successive steps in the operation have the disadvantage of entailing hospitalizing the patient for a relatively long period of time and of being complicated and expensive.
To overcome this drawback it has been envisaged for a heart valve to be replaced by a route which is not so invasive. International (PCT) applications Ser. Nos. WO 93/01768 and WO 97/28807, and U.S. Pat. Nos. 5,814,097, 5,370,685 and 5,545,214 illustrate some known fairly non-invasive techniques and instruments for performing these techniques.
The existing techniques are, however, considered not to be perfectly satisfactory and to be open to improvement. In particular, these techniques have the disadvantage of always involving placing the patient under extra-corporal circulation and temporarily stopping the heart; they are difficult to put into practice; they do not allow precise control over the diameter at which the native valve is cut with a view to subsequently calibrating the prosthetic valve; they run the risk that fragments of, often calcified, native valve will become dispersed into the organism, which may lead to an embolism, and the risks of perforating the wall of the aorta or the heart; they also introduce the risks of acute reflux of blood during ablation of the native valve.
The device according to the present invention has been designed with a view to alleviating the deficiencies of these techniques.
In particular, the object of the invention is to provide a device which is satisfactory as regards the cutting-away and replacement of the valve, by making it possible to perform the intervention without opening up the thorax, stopping the heart and/or opening up the heart, and by making it possible to prevent any dispersion of fragments of the removed valve into the circulatory system.
The terms xe2x80x9cdistalxe2x80x9d and xe2x80x9cproximalxe2x80x9d used hereinbelow to explain the invention are defined with respect to the direction in which the blood flows.
The device according to the invention comprises:
an elongate support element;
a first series of elongate blades arranged around the circumference of said elongate element; these blades are pivotably connected to the elongate element at their proximal longitudinal end and each have a cutting edge at their distal longitudinal end; these blades can pivot with respect to the elongate element between a furled position in which they are near to the wall of the elongate element so that they do not impede the introduction and sliding of the device into and in the bodily vessel in which the valve is located, particularly within the aorta, and an unfurled position in which these blades are deployed into a corolla in such a way that their cutting edges are placed in the continuation of one another and thus constitute a circular cutting edge;
a second series of blades which is arranged after said first series of blades in the distal direction; the blades of this second series of blades have a structure identical to that of the blades of said first series of blades except that these blades of this second series are connected to the elongate element by their distal longitudinal end and each have a cutting edge at their proximal longitudinal end;
means for bringing the blades of said first and second series of blades from their furled position to their unfurled position;
means for moving said series of blades axially toward one another, between a position in which these series of blades are away from each other and in which one series of blades can be placed axially on one side of the native valve while the other series of blades is placed axially on the other side of this valve, and a close-together position in which the circular cutting edges of these two series of blades are brought into mutual contact and thus cut through the native valve so as to detach it from said bodily vessel; and
means of identifying, by a percutaneous route, the axial position of the device with respect to the native valve so as to position each of the two aforementioned series of blades on one side of this valve.
The device according to the invention may be introduced percutaneously into said bodily vessel and slid along this vessel until each of the aforementioned series of blades is placed on one side of the valve. This position is identified using said identifying means.
A peripheral profusion or extra corporal circulation system may be set in place to facilitate the flow of the blood, with a view to preventing blood from pooling in the heart.
After the aforementioned positioning of the device, the blades of the two series of blades are deployed, then these two series are brought closer together until they cut through the valve. The shaping of these blades allows this cutting to be performed in a single operation, therefore without generating fragments likely to be dispersed into the circulatory system, or at the very least generating only very few such fragments; this shaping also allows precise control over the diameter at which the native valve is cut, with a view to subsequent calibration of the prosthetic valve.
The blades are then returned to the furled position.
The prosthetic valve is then put in place.
This valve may be separate from the device, in which case the latter is removed, then the prosthetic valve is introduced and positioned in the said bodily vessel by means of a separate device. As a preference, however, the device according to the invention comprises a proximal prosthetic valve, with a radially deployable structure, it being possible for this prosthetic valve to occupy a furled position in which it is near the wall of said elongate element and does not impede the introduction and sliding of the device into and in said bodily vessel, and an unfurled position in which it bears against the wall of this vessel and is able to replace the native heart valve.
The device thus allows the prosthetic valve to be introduced and positioned at the appropriate point in the bodily vessel, through the same action as the one which allowed the native valve to be cut out. After the latter has been cut out, the device is slid axially in the distal direction so as to position the prosthetic valve at the appropriate point in this vessel, after which this prosthetic valve is deployed. The device is then withdrawn and the cut-out native valve is recovered.
As a preference, said elongate support element is a tubular catheter.
This catheter thus allows the blood to flow through it during the time that the native valve is being cut away.
The cross section of the passage through this catheter may be large enough to allow the blood to flow through this passage, thus limiting or avoiding having to place the patient on extra corporal circulation. The catheter may also have a smaller diameter, making it easier for the device to be introduced into and slid along the bodily vessel, but it then becomes necessary to provide peripheral circulation through an external assistance system such as an extra corporal circulation system.
The catheter comprises a lateral distal opening to allow the blood to reach the bodily vessel, for example the ascending aorta, this opening being formed in such a way that the length of catheter through which the blood flows is as short as possible.
As a preference, the device comprises a distal inflatable balloon, placed at the exterior face of said elongate element; this balloon is shaped to be able to occupy a furled position in which it has a cross section such that it does not impede the sliding introduction of the device into said bodily vessel, and an unfurled position in which it occupies all of the space between the exterior face of said elongate element and the wall of said bodily vessel and, via a peripheral edge that it comprises, bears against this wall.
The balloon is inflated after the series of blades have been positioned one on each side of the native valve, so as to prevent blood reflux during the ablation of the native valve. When said elongate element is a catheter, this balloon also allows this blood to be made to flow only through the catheter.
Once the prosthetic valve has been put in place, the balloon is returned to its furled position so as to re-establish the flow of blood through the bodily vessel.
As a preference, the device comprises a distal filter made of flexible material placed at the exterior face of said elongate element; this filter is shaped to be able to occupy a furled position in which it has a cross section such that it does not impede the introduction and sliding of the device into and in said bodily vessel, and an unfurled position in which it occupies all of the space between the exterior face of said elongate element and the wall of this vessel and, via a peripheral edge that it comprises, bears against this wall.
This filter makes it possible to collect any fragments that may have been generated by the cutting-away of the valve, and to retain them so that they can be removed from the blood circulation.
The device may comprise means for moving said series of blades in the axial direction independently of said balloon and/or of said filter. Once deployed, this or these do not need to be shifted axially in the bodily vessel during the aforementioned axial moving of the series of blades.
Said balloon and/or said filter may also be separate from the device, being mounted on an elongate support element specific to them.
In the event of operations on a mitral valve, this balloon and/or this filter are introduced into the aorta via a peripheral arterial route, and the device for its part is introduced into the heart through the peripheral venous system, as far as the right atrium then into the left atrium through the interatrial septum as far as the mitral valve.
The prosthetic valve may advantageously comprise an armature made of a shape memory material, particularly a nickel-titanium alloy known by the name of xe2x80x9cNITINOLxe2x80x9d.
This same valve may comprise valve leaflets made of biological material (preserved animal or human valve leaflets) or valve leaflets made of a synthetic material such as a polymer.